[imager.git] / paste.im

#include "imager.h"

/*
=item i_copyto(C<dest>, C<src>, C<x1>, C<y1>, C<x2>, C<y2>, C<tx>, C<ty>)

=category Image

Copies image data from the area (C<x1>,C<y1>)-[C<x2>,C<y2>] in the
source image to a rectangle the same size with it's top-left corner at
(C<tx>,C<ty>) in the destination image.

If C<x1> > C<x2> or C<y1> > C<y2> then the corresponding co-ordinates
are swapped.

=cut
*/

void
i_copyto(i_img *im, i_img *src, int x1, int y1, int x2, int y2, int tx, int ty) {
  int y, t, ttx, tty;
  
  if (x2<x1) { t=x1; x1=x2; x2=t; }
  if (y2<y1) { t=y1; y1=y2; y2=t; }
  if (tx < 0) {
    /* adjust everything equally */
    x1 += -tx;
    x2 += -tx;
    tx = 0;
  }
  if (ty < 0) {
    y1 += -ty;
    y2 += -ty;
    ty = 0;
  }
  if (x1 >= src->xsize || y1 >= src->ysize)
    return; /* nothing to do */
  if (x2 > src->xsize)
    x2 = src->xsize;
  if (y2 > src->ysize)
    y2 = src->ysize;
  if (x1 == x2 || y1 == y2)
    return; /* nothing to do */

  mm_log((1,"i_copyto(im* %p, src %p, x1 %d, y1 %d, x2 %d, y2 %d, tx %d, ty %d)\n",
	  im, src, x1, y1, x2, y2, tx, ty));

#code im->bits == i_8_bits
  IM_COLOR *row = mymalloc(sizeof(IM_COLOR) * (x2-x1));
  tty = ty;
  for(y=y1; y<y2; y++) {
    ttx = tx;
    IM_GLIN(src, x1, x2, y, row);
    if (src->channels != im->channels)
      IM_ADAPT_COLORS(im->channels, src->channels, row, x2-x1);
    IM_PLIN(im, tx, tx+x2-x1, tty, row);
    tty++;
  }
  myfree(row);
#/code
}

#define color_to_grey(col) ((col)->rgb.r * 0.222  + (col)->rgb.g * 0.707 + (col)->rgb.b * 0.071)

#code
void
#ifdef IM_EIGHT_BIT
i_adapt_colors
#else
i_adapt_fcolors
#endif
(int out_channels, int in_channels, IM_COLOR *colors, 
	       size_t count) {
  if (out_channels == in_channels)
    return;
  if (count == 0)
    return;

  switch (out_channels) {
  case 1:
    {
      switch (in_channels) {
      case 2:
	/* apply alpha against a black background */
	while (count) {
	  colors->channel[0] = colors->channel[0] * colors->channel[1] / IM_SAMPLE_MAX;
	  ++colors;
	  --count;
	}
	return;

      case 3:
	/* convert to grey */
	while (count) {
	  colors->channel[0] = IM_ROUND(color_to_grey(colors));
	  ++colors;
	  --count;
	}
	return;
	    
      case 4:
	while (count) {
	  colors->channel[0] = IM_ROUND(color_to_grey(colors) * colors->channel[3] / IM_SAMPLE_MAX);
	  ++colors;
	  --count;
	}
	return;

      default:
	i_fatal(3, "i_adapt_colors: in_channels of %d invalid\n", in_channels);
	return; /* avoid warnings */
      }
    }

  case 2:
    {
      switch (in_channels) {
      case 1:
	while (count) {
	  colors->channel[1] = IM_SAMPLE_MAX;
	  ++colors;
	  --count;
	}
	return;

      case 3:
	while (count) {
	  colors->channel[0] = IM_ROUND(color_to_grey(colors));
	  colors->channel[1] = IM_SAMPLE_MAX;
	  ++colors;
	  --count;
	}
	return;

      case 4:
	while (count) {
	  colors->channel[0] = IM_ROUND(color_to_grey(colors));
	  colors->channel[1] = colors->channel[3];
	  ++colors;
	  --count;
	}
	return;

      default:
	i_fatal(3, "i_adapt_colors: in_channels of %d invalid\n", in_channels);
	return; /* avoid warnings */
      }
    }

  case 3:
    {
      switch (in_channels) {
      case 1:
	while (count) {
	  colors->channel[1] = colors->channel[2] = colors->channel[0];
	  ++colors;
	  --count;
	}
	return;

      case 2:
	while (count) {
	  int alpha = colors->channel[1];
	  colors->channel[0] = colors->channel[1] = colors->channel[2] =
	    IM_ROUND(colors->channel[0] * alpha / IM_SAMPLE_MAX);
	  ++colors;
	  --count;
	}
	return;

      case 4:
	while (count) {
	  int alpha = colors->channel[3];
	  colors->channel[0] = 
	    IM_ROUND(colors->channel[0] * alpha / IM_SAMPLE_MAX);
	  colors->channel[1] = 
	    IM_ROUND(colors->channel[1] * alpha / IM_SAMPLE_MAX);
	  colors->channel[2] = 
	    IM_ROUND(colors->channel[2] * alpha / IM_SAMPLE_MAX);
	  ++colors;
	  --count;
	}
	return;

      default:
	i_fatal(3, "i_adapt_colors: in_channels of %d invalid\n", in_channels);
	return; /* avoid warnings */
      }
    }

  case 4:
    {
      switch (in_channels) {
      case 1:
	while (count) {
	  colors->channel[1] = colors->channel[2] = colors->channel[0];
	  colors->channel[3] = IM_SAMPLE_MAX;
	  ++colors;
	  --count;
	}
	return;

      case 2:
	while (count) {
	  colors->channel[3] = colors->channel[1];
	  colors->channel[1] = colors->channel[2] = colors->channel[0];
	  ++colors;
	  --count;
	}
	return;

      case 3:
	while (count) {
	  colors->channel[3] = IM_SAMPLE_MAX;
	  ++colors;
	  --count;
	}
	return;

      default:
	i_fatal(3, "i_adapt_colors: in_channels of %d invalid\n", in_channels);
	return; /* avoid warnings */
      }
    }

  default:
    i_fatal(3, "i_adapt_colors: out_channels of %d invalid\n", out_channels);
    return; /* avoid warnings */
  }
}

void
#ifdef IM_EIGHT_BIT
i_adapt_colors_bg
#else
i_adapt_fcolors_bg
#endif
(int out_channels, int in_channels, IM_COLOR *colors, 
	       size_t count, IM_COLOR const *bg) {
  if (out_channels == in_channels)
    return;
  if (count == 0)
    return;

  switch (out_channels) {
  case 2:
  case 4:
    IM_ADAPT_COLORS(out_channels, in_channels, colors, count);
    return;

  case 1:
    switch (in_channels) {
    case 3:
      IM_ADAPT_COLORS(out_channels, in_channels, colors, count);
      return;

    case 2:
      {
	/* apply alpha against our given background */
	IM_WORK_T grey_bg = IM_ROUND(color_to_grey(bg));
	while (count) {
	  colors->channel[0] = 
	    (colors->channel[0] * colors->channel[1] +
	     grey_bg * (IM_SAMPLE_MAX - colors->channel[1])) / IM_SAMPLE_MAX;
	  ++colors;
	  --count;
	}
      }
      break;

    case 4:
      {
	IM_WORK_T grey_bg = IM_ROUND(color_to_grey(bg));
	while (count) {
	  IM_WORK_T src_grey = IM_ROUND(color_to_grey(colors));
	  colors->channel[0] =
	    (src_grey * colors->channel[3]
	     + grey_bg * (IM_SAMPLE_MAX - colors->channel[3])) / IM_SAMPLE_MAX;
	  ++colors;
	  --count;
	}
      }
      break;
    }
    break;
      
  case 3:
    switch (in_channels) {
    case 1:
      IM_ADAPT_COLORS(out_channels, in_channels, colors, count);
      return;

    case 2:
      {
	while (count) {
	  int ch;
	  IM_WORK_T src_grey = colors->channel[0];
	  IM_WORK_T src_alpha = colors->channel[1];
	  for (ch = 0; ch < 3; ++ch) {
	    colors->channel[ch] =
	      (src_grey * src_alpha
	       + bg->channel[ch] * (IM_SAMPLE_MAX - src_alpha)) 
	      / IM_SAMPLE_MAX;
	  }
	  ++colors;
	  --count;
	}
      }
      break;

    case 4:
      {
	while (count) {
	  int ch;
	  IM_WORK_T src_alpha = colors->channel[3];
	  for (ch = 0; ch < 3; ++ch) {
	    colors->channel[ch] =
	      (colors->channel[ch] * src_alpha
	       + bg->channel[ch] * (IM_SAMPLE_MAX - src_alpha)) 
	      / IM_SAMPLE_MAX;
	  }
	  ++colors;
	  --count;
	}
      }
      break;
    }
    break;
  }
}

/*
=item i_gsamp_bg(im, l, r, y, samples, out_channels, bg)

=item i_gsampf_bg(im, l, r, y, samples, out_channels, bg)

This is similar to i_adapt_colors_bg() except it can only strip an
alpha channel.  It cannot be used to convert a source RGB image to
greyscale.

The samples parameter MUST include enough space for all samples of the
source image.

=cut
*/
int
#ifdef IM_EIGHT_BIT
i_gsamp_bg
#else
i_gsampf_bg
#endif
(i_img *im, int l, int r, int y, IM_SAMPLE_T *samples, 
 int out_channels, IM_COLOR const *bg) {
  if (out_channels == im->channels)
    return IM_GSAMP(im, l, r, y, samples, NULL, im->channels);
  
  switch (out_channels) {
  case 1:
    switch (im->channels) {
    case 2:
      {
	int x;
	IM_SAMPLE_T *inp = samples, *outp = samples;
	IM_WORK_T grey_bg = IM_ROUND(color_to_grey(bg));
	int count;

	count = IM_GSAMP(im, l, r, y, samples, NULL, im->channels);
	if (!count)
	  return 0;
	
	for (x = l; x < r; ++x) {
	  *outp++ = ( inp[0] * inp[1] +
		      grey_bg * (IM_SAMPLE_MAX - inp[1])) / IM_SAMPLE_MAX;
	  inp += 2;
	}

	return count;
      }
      break;

    default:
      i_fatal(0, "i_gsamp_bg() can only remove alpha channels");
      break;
    }
    break;
  case 3:
    switch (im->channels) {
    case 1:
      {
	int channels[3] = { 0, 0, 0 };
	return IM_GSAMP(im, l, r, y, samples, channels, out_channels);
      }
    case 2:
      {
	int x, ch;
	IM_SAMPLE_T *inp = samples, *outp = samples;
	int count;
	int channels[4] = { 0, 0, 0, 1 };

	count = IM_GSAMP(im, l, r, y, samples, channels, im->channels);
	if (!count)
	  return 0;
	
	for (x = l; x < r; ++x) {
	  IM_WORK_T alpha = inp[3];
	  for (ch = 0; ch < 3; ++ch) {
	    *outp++ = ( *inp++ * alpha +
			bg->channel[ch] * (IM_SAMPLE_MAX - alpha)) / IM_SAMPLE_MAX;
	  }
	  ++inp;
	}

	return count;
      }

    case 4:
      {
	int x, ch;
	IM_SAMPLE_T *inp = samples, *outp = samples;
	int count;

	count = IM_GSAMP(im, l, r, y, samples, NULL, im->channels);
	if (!count)
	  return 0;
	
	for (x = l; x < r; ++x) {
	  IM_WORK_T alpha = inp[3];
	  for (ch = 0; ch < 3; ++ch) {
	    *outp++ = ( *inp++ * alpha +
			bg->channel[ch] * (IM_SAMPLE_MAX - alpha)) / IM_SAMPLE_MAX;
	  }
	  ++inp;
	}

	return count;
      }
      break;
    default:
      i_fatal(0, "i_gsamp_bg() can only remove alpha channels");
      break;
    }
    break;

  default:
    i_fatal(0, "i_gsamp_bg() can only remove alpha channels");
  }

  return 0;
}

#/code
Commit	Line	Data
9b1ec2b8 TC	1	#include "imager.h"
	2
	3	/*
5715f7c3	4	=item i_copyto(C<dest>, C<src>, C<x1>, C<y1>, C<x2>, C<y2>, C<tx>, C<ty>)
9b1ec2b8 TC	5
	6	=category Image
	7
5715f7c3 TC	8	Copies image data from the area (C<x1>,C<y1>)-[C<x2>,C<y2>] in the
	9	source image to a rectangle the same size with it's top-left corner at
	10	(C<tx>,C<ty>) in the destination image.
9b1ec2b8	11
5715f7c3 TC	12	If C<x1> > C<x2> or C<y1> > C<y2> then the corresponding co-ordinates
5715f7c3 TC	13	are swapped.
9b1ec2b8 TC	14
	15	=cut
	16	*/
	17
	18	void
	19	i_copyto(i_img im, i_img src, int x1, int y1, int x2, int y2, int tx, int ty) {
a827f5b4	20	int y, t, ttx, tty;
9b1ec2b8 TC	21
	22	if (x2<x1) { t=x1; x1=x2; x2=t; }
	23	if (y2<y1) { t=y1; y1=y2; y2=t; }
	24	if (tx < 0) {
	25	/* adjust everything equally */
	26	x1 += -tx;
	27	x2 += -tx;
	28	tx = 0;
	29	}
	30	if (ty < 0) {
	31	y1 += -ty;
	32	y2 += -ty;
	33	ty = 0;
	34	}
	35	if (x1 >= src->xsize \|\| y1 >= src->ysize)
	36	return; /* nothing to do */
	37	if (x2 > src->xsize)
	38	x2 = src->xsize;
	39	if (y2 > src->ysize)
	40	y2 = src->ysize;
	41	if (x1 == x2 \|\| y1 == y2)
	42	return; /* nothing to do */
	43
	44	mm_log((1,"i_copyto(im* %p, src %p, x1 %d, y1 %d, x2 %d, y2 %d, tx %d, ty %d)\n",
	45	im, src, x1, y1, x2, y2, tx, ty));
	46
	47	#code im->bits == i_8_bits
	48	IM_COLOR row = mymalloc(sizeof(IM_COLOR) (x2-x1));
	49	tty = ty;
	50	for(y=y1; y<y2; y++) {
	51	ttx = tx;
	52	IM_GLIN(src, x1, x2, y, row);
	53	if (src->channels != im->channels)
	54	IM_ADAPT_COLORS(im->channels, src->channels, row, x2-x1);
	55	IM_PLIN(im, tx, tx+x2-x1, tty, row);
	56	tty++;
	57	}
	58	myfree(row);
	59	#/code
	60	}
	61
	62	#define color_to_grey(col) ((col)->rgb.r * 0.222 + (col)->rgb.g * 0.707 + (col)->rgb.b * 0.071)
	63
	64	#code
	65	void
	66	#ifdef IM_EIGHT_BIT
	67	i_adapt_colors
	68	#else
	69	i_adapt_fcolors
	70	#endif
	71	(int out_channels, int in_channels, IM_COLOR *colors,
	72	size_t count) {
9b1ec2b8 TC	73	if (out_channels == in_channels)
	74	return;
	75	if (count == 0)
	76	return;
	77
	78	switch (out_channels) {
	79	case 1:
	80	{
	81	switch (in_channels) {
	82	case 2:
	83	/* apply alpha against a black background */
	84	while (count) {
	85	colors->channel[0] = colors->channel[0] * colors->channel[1] / IM_SAMPLE_MAX;
	86	++colors;
	87	--count;
	88	}
	89	return;
	90
	91	case 3:
	92	/* convert to grey */
	93	while (count) {
	94	colors->channel[0] = IM_ROUND(color_to_grey(colors));
	95	++colors;
	96	--count;
	97	}
	98	return;
	99
	100	case 4:
	101	while (count) {
	102	colors->channel[0] = IM_ROUND(color_to_grey(colors) * colors->channel[3] / IM_SAMPLE_MAX);
	103	++colors;
	104	--count;
	105	}
	106	return;
	107
	108	default:
	109	i_fatal(3, "i_adapt_colors: in_channels of %d invalid\n", in_channels);
	110	return; /* avoid warnings */
	111	}
	112	}
	113
	114	case 2:
	115	{
	116	switch (in_channels) {
	117	case 1:
	118	while (count) {
	119	colors->channel[1] = IM_SAMPLE_MAX;
	120	++colors;
	121	--count;
	122	}
	123	return;
	124
	125	case 3:
	126	while (count) {
	127	colors->channel[0] = IM_ROUND(color_to_grey(colors));
	128	colors->channel[1] = IM_SAMPLE_MAX;
	129	++colors;
	130	--count;
	131	}
	132	return;
	133
	134	case 4:
	135	while (count) {
	136	colors->channel[0] = IM_ROUND(color_to_grey(colors));
137	colors->channel[1] = colors->channel[3];
138	++colors;
139	--count;
140	}
141	return;
142
143	default:
144	i_fatal(3, "i_adapt_colors: in_channels of %d invalid\n", in_channels);
145	return; /* avoid warnings */
146	}
147	}
148
149	case 3:
150	{
151	switch (in_channels) {
152	case 1:
153	while (count) {
154	colors->channel[1] = colors->channel[2] = colors->channel[0];
155	++colors;
156	--count;
157	}
158	return;
159
160	case 2:
161	while (count) {
162	int alpha = colors->channel[1];
163	colors->channel[0] = colors->channel[1] = colors->channel[2] =
164	IM_ROUND(colors->channel[0] * alpha / IM_SAMPLE_MAX);
165	++colors;
166	--count;
167	}
168	return;
169
170	case 4:
171	while (count) {
172	int alpha = colors->channel[3];
173	colors->channel[0] =
174	IM_ROUND(colors->channel[0] * alpha / IM_SAMPLE_MAX);
175	colors->channel[1] =
176	IM_ROUND(colors->channel[1] * alpha / IM_SAMPLE_MAX);
177	colors->channel[2] =
178	IM_ROUND(colors->channel[2] * alpha / IM_SAMPLE_MAX);
179	++colors;
180	--count;
181	}
182	return;
183
184	default:
185	i_fatal(3, "i_adapt_colors: in_channels of %d invalid\n", in_channels);
186	return; /* avoid warnings */
187	}
188	}
189
190	case 4:
191	{
192	switch (in_channels) {
193	case 1:
194	while (count) {
195	colors->channel[1] = colors->channel[2] = colors->channel[0];
196	colors->channel[3] = IM_SAMPLE_MAX;
197	++colors;
198	--count;
199	}
200	return;
201
202	case 2:
203	while (count) {
204	colors->channel[3] = colors->channel[1];
205	colors->channel[1] = colors->channel[2] = colors->channel[0];
206	++colors;
207	--count;
208	}
209	return;
210
211	case 3:
212	while (count) {
213	colors->channel[3] = IM_SAMPLE_MAX;
214	++colors;
215	--count;
216	}
217	return;
218
219	default:
220	i_fatal(3, "i_adapt_colors: in_channels of %d invalid\n", in_channels);
221	return; /* avoid warnings */
222	}
223	}
224
225	default:
226	i_fatal(3, "i_adapt_colors: out_channels of %d invalid\n", out_channels);
227	return; /* avoid warnings */
228	}
229	}
230
6e4af7d4 TC	231	void
	232	#ifdef IM_EIGHT_BIT
	233	i_adapt_colors_bg
	234	#else
	235	i_adapt_fcolors_bg
	236	#endif
	237	(int out_channels, int in_channels, IM_COLOR *colors,
	238	size_t count, IM_COLOR const *bg) {
	239	if (out_channels == in_channels)
	240	return;
	241	if (count == 0)
	242	return;
	243
	244	switch (out_channels) {
	245	case 2:
	246	case 4:
	247	IM_ADAPT_COLORS(out_channels, in_channels, colors, count);
	248	return;
	249
	250	case 1:
	251	switch (in_channels) {
	252	case 3:
	253	IM_ADAPT_COLORS(out_channels, in_channels, colors, count);
	254	return;
	255
	256	case 2:
	257	{
	258	/* apply alpha against our given background */
	259	IM_WORK_T grey_bg = IM_ROUND(color_to_grey(bg));
	260	while (count) {
	261	colors->channel[0] =
	262	(colors->channel[0] * colors->channel[1] +
	263	grey_bg * (IM_SAMPLE_MAX - colors->channel[1])) / IM_SAMPLE_MAX;
	264	++colors;
	265	--count;
	266	}
	267	}
	268	break;
	269
	270	case 4:
	271	{
	272	IM_WORK_T grey_bg = IM_ROUND(color_to_grey(bg));
	273	while (count) {
	274	IM_WORK_T src_grey = IM_ROUND(color_to_grey(colors));
	275	colors->channel[0] =
	276	(src_grey * colors->channel[3]
	277	+ grey_bg * (IM_SAMPLE_MAX - colors->channel[3])) / IM_SAMPLE_MAX;
	278	++colors;
	279	--count;
	280	}
	281	}
	282	break;
	283	}
	284	break;
	285
	286	case 3:
	287	switch (in_channels) {
	288	case 1:
	289	IM_ADAPT_COLORS(out_channels, in_channels, colors, count);
	290	return;
	291
	292	case 2:
	293	{
	294	while (count) {
295	int ch;
296	IM_WORK_T src_grey = colors->channel[0];
297	IM_WORK_T src_alpha = colors->channel[1];
298	for (ch = 0; ch < 3; ++ch) {
299	colors->channel[ch] =
300	(src_grey * src_alpha
301	+ bg->channel[ch] * (IM_SAMPLE_MAX - src_alpha))
302	/ IM_SAMPLE_MAX;
303	}
304	++colors;
305	--count;
306	}
307	}
308	break;
309
310	case 4:
311	{
312	while (count) {
313	int ch;
314	IM_WORK_T src_alpha = colors->channel[3];
315	for (ch = 0; ch < 3; ++ch) {
316	colors->channel[ch] =
317	(colors->channel[ch] * src_alpha
318	+ bg->channel[ch] * (IM_SAMPLE_MAX - src_alpha))
319	/ IM_SAMPLE_MAX;
320	}
321	++colors;
322	--count;
323	}
324	}
325	break;
326	}
327	break;
328	}
2a31a4b4 TC	329	}
	330
	331	/*
	332	=item i_gsamp_bg(im, l, r, y, samples, out_channels, bg)
	333
	334	=item i_gsampf_bg(im, l, r, y, samples, out_channels, bg)
	335
	336	This is similar to i_adapt_colors_bg() except it can only strip an
	337	alpha channel. It cannot be used to convert a source RGB image to
	338	greyscale.
	339
	340	The samples parameter MUST include enough space for all samples of the
	341	source image.
	342
	343	=cut
	344	*/
	345	int
	346	#ifdef IM_EIGHT_BIT
	347	i_gsamp_bg
	348	#else
	349	i_gsampf_bg
	350	#endif
	351	(i_img im, int l, int r, int y, IM_SAMPLE_T samples,
	352	int out_channels, IM_COLOR const *bg) {
	353	if (out_channels == im->channels)
	354	return IM_GSAMP(im, l, r, y, samples, NULL, im->channels);
	355
	356	switch (out_channels) {
	357	case 1:
	358	switch (im->channels) {
	359	case 2:
	360	{
	361	int x;
	362	IM_SAMPLE_T inp = samples, outp = samples;
	363	IM_WORK_T grey_bg = IM_ROUND(color_to_grey(bg));
	364	int count;
	365
	366	count = IM_GSAMP(im, l, r, y, samples, NULL, im->channels);
	367	if (!count)
	368	return 0;
	369
	370	for (x = l; x < r; ++x) {
	371	outp++ = ( inp[0] inp[1] +
	372	grey_bg * (IM_SAMPLE_MAX - inp[1])) / IM_SAMPLE_MAX;
	373	inp += 2;
	374	}
	375
	376	return count;
	377	}
	378	break;
	379
	380	default:
	381	i_fatal(0, "i_gsamp_bg() can only remove alpha channels");
	382	break;
	383	}
	384	break;
	385	case 3:
	386	switch (im->channels) {
	387	case 1:
	388	{
	389	int channels[3] = { 0, 0, 0 };
	390	return IM_GSAMP(im, l, r, y, samples, channels, out_channels);
	391	}
	392	case 2:
393	{
394	int x, ch;
395	IM_SAMPLE_T inp = samples, outp = samples;
396	int count;
397	int channels[4] = { 0, 0, 0, 1 };
398
399	count = IM_GSAMP(im, l, r, y, samples, channels, im->channels);
400	if (!count)
401	return 0;
402
403	for (x = l; x < r; ++x) {
404	IM_WORK_T alpha = inp[3];
405	for (ch = 0; ch < 3; ++ch) {
406	outp++ = ( inp++ * alpha +
407	bg->channel[ch] * (IM_SAMPLE_MAX - alpha)) / IM_SAMPLE_MAX;
408	}
409	++inp;
410	}
411
412	return count;
413	}
414
415	case 4:
416	{
417	int x, ch;
418	IM_SAMPLE_T inp = samples, outp = samples;
419	int count;
420
421	count = IM_GSAMP(im, l, r, y, samples, NULL, im->channels);
422	if (!count)
423	return 0;
424
425	for (x = l; x < r; ++x) {
426	IM_WORK_T alpha = inp[3];
427	for (ch = 0; ch < 3; ++ch) {
428	outp++ = ( inp++ * alpha +
429	bg->channel[ch] * (IM_SAMPLE_MAX - alpha)) / IM_SAMPLE_MAX;
430	}
431	++inp;
432	}
433
434	return count;
435	}
436	break;
437	default:
438	i_fatal(0, "i_gsamp_bg() can only remove alpha channels");
439	break;
440	}
441	break;
442
443	default:
444	i_fatal(0, "i_gsamp_bg() can only remove alpha channels");
445	}
6e4af7d4	446
2a31a4b4	447	return 0;
6e4af7d4 TC	448	}
6e4af7d4 TC	449
9b1ec2b8 TC	450	#/code
9b1ec2b8 TC	451